Propionate assimilation in the flagellate Polytomella caeca. An inducible mitochondrial enzyme system.
1. The assimilation of propionate by Polytomella caeca involves the beta-oxidation of this fatty acid. 2. Propionate-grown cells immediately oxidize propionate, beta-hydroxypropionate, malonic semialdehyde and acetate; acetate-grown cells oxidize propionate rapidly only after a lag of 2hr., and this adaptation of resting cells to propionate involves the formation of the enzymes of beta-oxidation. 3. The beta-hydroxypropionate dehydrogenase and malonic semialdehyde dehydrogenase activities of both propionate-grown and propionate-adapted cells are partly located in mitochondrial fractions. 4. Mitochondria isolated from propionate-grown cells, and also those from acetate-grown cells fully adapted to propionate, oxidize succinate, alpha-oxoglutarate, beta-hydroxypropionate and malonic semialdehyde; oxidation of these substrates is tightly coupled to the phosphorylation of ADP. 5. Mitochondria from acetate-grown cells exhibit ADP-dependent oxidation of succinate and alpha-oxoglutarate, but do not oxidize beta-hydroxypropionate or malonic semialdehyde. Mitochondria isolated from acetate-grown cells adapted to propionate for 5hr. slowly oxidize beta-hydroxypropionate and malonic semialdehyde, but no tightly coupled phosphorylation is detectable. 6. Two of the inducible enzymes of propionate oxidation are located within the NAD-impermeable barrier and appear to be membrane-bound. 7. The formation of the inducible enzymes is inhibited by cycloheximide and actinomycin D, but not by chloramphenicol.
D000085:Acetates / Q000378:metabolism; D000227:Adenine Nucleotides / Q000378:metabolism; D000429:Alcohol Oxidoreductases / Q000032:analysis; D000818:Animals; D002463:Cell Membrane Permeability; D003513:Cycloheximide / Q000494:pharmacology; D003609:Dactinomycin / Q000494:pharmacology; D003864:Depression, Chemical; D004790:Enzyme Induction; D056890:Eukaryota / Q000201:enzymology* / Q000378:metabolism; D005977:Glutarates / Q000378:metabolism; D008314:Malonates / Q000378:metabolism; D008928:Mitochondria / Q000201:enzymology* / Q000378:metabolism; D010084:Oxidation-Reduction; D010085:Oxidative Phosphorylation; D010088:Oxidoreductases / Q000032:analysis; D011422:Propionates / Q000378:metabolism*; D013386:Succinates / Q000378:metabolism; D013997:Time Factors
D000085:Acetates; D000227:Adenine Nucleotides; D005977:Glutarates; D008314:Malonates; D011422:Propionates; D013386:Succinates; D003609:Dactinomycin; D003513:Cycloheximide; D010088:Oxidoreductases; D000429:Alcohol Oxidoreductases